The present invention relates to a sheet separator for use in electrophotographic copying machines, and more particularly, to such an apparatus which separates a copy sheet as held attracted to the surface of a rotating photosensitive member of the machine from said surface.
In electrophotographic copying machines, an electrostatic latent image or a toner image thereof is transferred onto a copy sheet by an arrangement which brings the surface of the photosensitive member which carries the image into contact with the copy sheet. When brought into contact with the photosensitive member, the copy sheet is held attracted to the surface under the influence of an electric charge which is present thereon. The electrostatic latent image is formed by exposing a uniformly charged surface of the photosensitive member to a light image of an original being copied. Where the copying machine is of the type utilizing a transfer of latent image, the latent image formed is transferred onto a copy sheet, and the tranferred image on the latter is converted into a visual image by using either a toner containing developing solution or a dry developer. However, if the copying machine is of the type utilizing a transfer of visual image, the latent image formed on the surface of the photosensitive member is developed before it is transferred onto the copy sheet.
Several arrangements are known which may be used to separate a copy sheet from the photosensitive member when it is held attracted thereto. In one form, claws are maintained in gentle abutting relationship with the surface of the photosensitive member so that the leading edge of the copy sheet may be stripped off the surface as it comes to engage the claws. This however suffers from the likelihood of damaging or impairing the surface of the photosensitive member.
In another form of sheet separator, a jet of air is directed toward the leading edge of the copy sheet in a direction opposite to the direction of rotation of the photosensitive member so as to deflect the edge and the sheet away from the surface of the member. However, an air spray of a high pressure must be provided in order to separate the copy sheet which is held attracted to the photosensitive member.